3 Bantams in that space should be fine for now. They are only two months old, so won't reach full size until 5-6 months. Even then, space recommendations for bantams are less than full size fowl, because bantams are smaller. Pay attention to how they act, and how they treat each other, and you may be able to tell how stressed they are. But that space looks good to me - I think they'll be okay until you have time to expand the run.
I like that you have plenty of things to block line of sight so they can run away from each other and escape, they have a combo of shade and sun, plenty of ventilation, and can all eat and drink at once without one bird running the others off too much. I'd keep an eye on the ventilation for the coop - it may need more this summer depending on your weather. Keep/put a thermometer in there and check during the hottest part of the day. Where I live in North Alabama, I need at least 3 sq feet open space above the chickens' heads per chicken (for large fowl) to get adequate coop ventilation. Due to the hot and humid weather here, I skipped the coop totally and they live year-round in a covered run.
If you search around on this site, you may find more information. General recommendation for standard fowl is 10 sq ft in the run and 4 sq ft in the coop per chicken, but can be less or more depending on the individual chickens. Also, 3 sq ft per chicken ventilation at least if you live in weather similar to South Carolina, Virginia, or Texas and areas southward.
Bantam recommendations are less than that, but I don't remember them.